The Government says moves by Japan to resume whaling in the southern ocean are "worrying".

Japanese Prime Minister Shinzo Abe has announced Japan will increase efforts to resume commercial whaling, despite stopping the practice following an International Court of Justice ruling in March.

"I want to aim for the resumption of commercial whaling by conducting whaling research in order to obtain scientific data indispensable for the management of whale resources," Abe said yesterday.

"To that end, I will step up efforts further to get understanding from the international community."

In March the international court ruled Japan's government-subsidised whaling programme in the Southern Ocean was for commercial purposes, rather than scientific purposes as Japan had claimed.

Foreign Affairs Minister Murray McCully said today that it wasn't clear what Abe was proposing in the short term."[But] the fact that he has told a parliamentary committee [in Japan] that he wants to aim towards the resumption of commercial whaling is both unfortunate and unhelpful," he said.

The international court had laid down "clear guidelines" for any future research whaling and the New Zealand Government had welcomed Japan's previous statement it would study and abide by the court's ruling, he said.

"As a country that places a high value on its good international citizenship, we hope and expect that Japan will continue to respect the ICJ decision," McCully said.

Abe said whaling was an important activity to Japanese people, who had a great respect for the animals, and it was "regrettable that this part of Japanese culture is not understood".

Australia, backed by New Zealand, led the successful case against Japan which saw Japanese whaling in the Antarctic stopped, though the hunting of Minke whales along Japan's coast was not.

"The ICJ ruled definitively that Japan's previous whaling programme was illegal, it was simply a ruse, a guise for commercial whaling," he said, adding the comments were "deeply troubling."

Hughes said domestic politics could have lead to Abe's turnaround and called on the New Zealand government to send Japan a strong message about its opposition to whaling.

Greenpeace's New Zealand director Bunny McDiarmid said the latest move made no sense.

"This just seems like a change of heart," she said.

"Hardly anyone in Japan eats whale meat now, the markets are collapsing and whaling is losing money - it takes an enormous amount of government subsidisation to actually keep the whole train on the tracks."